1. Field of the Invention
The invention relates to a flywheel assembly, and more particularly to a flywheel assembly for transmitting torque from a crankshaft of an engine to an input shaft of a transmission.
2. Background Information
Generally, a flywheel is coupled to a crankshaft of an engine and serves to absorb the combustion vibrations of the engine. In a flywheel assembly known in the prior art, a damper mechanism is combined with the flywheel, and a torsional vibration damping system is divided into input and output sides with respect to the damper mechanism.
The flywheel assembly is formed of, e.g., a first flywheel on the input side, a second flywheel on the output side and a damper mechanism for elastically coupling these flywheels together in the rotational direction. The damper mechanism includes a plurality of coil springs, and further includes a friction generating mechanism and a viscous resistance generating mechanism. A clutch cover assembly is attached to a second flywheel, and a frictional coupling portion of the clutch disk assembly is arranged between a friction surface of the second flywheel and a pressing surface of a pressure plate. The clutch disk assembly is coupled to the input shaft of the transmission.
The flywheel assembly is configured to transmit a torque directly to the input shaft of the transmission without passing the torque through the clutch cover assembly and the clutch disk assembly. The flywheel assembly has a damper mechanism similar to the damper mechanism of the clutch disk assembly, and has a hub coupled to the input shaft. The flywheel is fixed to both or either of members on input and output sides of the damper mechanism.
The flywheel assembly transmitting the torque directly to the input shaft of the transmission includes a pair of disk shaped members, which are fixed together and are coupled to the flywheel, a hub, which has a flange arranged between the paired disk shaped members and is configured to transmit the torque to the input shaft, and an elastic member, which is arranged in the rotating direction between the disk shaped member pair and the flange, and is compressed in the rotating direction when relative rotation occurs therebetween. The flywheel is arranged between radially outer portions of the paired disk shaped members, and is fixed thereto by rivets.
The aforementioned flywheel assembly suffers from the following two problems.
First, the flywheel assembly does not have a torsion angle stopper for restricting the relative rotation or torsion angle between the disk shaped member on the input side and the hub. Therefore, when a shock torque is applied, the coil spring may receive an excessively large torque, and thus may be broken, or its durability may be impaired.
Second, the disk shaped member on the input side extends radially outward beyond the outer periphery of the hub flange, and thereby provides a riveting portion. Therefore, the radial position of the rivets cannot be shifted sufficiently toward the center of the disk shaped member so that the damper mechanism and therefore the flywheel assembly cannot have sufficiently small outer diameters.
Thus, an object of the invention is to provide a flywheel assembly configured to transmit a torque directly to an input shaft of a transmission, and particularly one which can prevent input of an excessively large torque to an elastic member.
Another object of the invention is to provide a flywheel assembly configured to transmit a torque directly to an input shaft of a transmission, and particularly one which has a sufficiently reduced radial size.